Monophonic electronic musical instrument of equal tempered scale

ABSTRACT

A monophonic electronic musical instrument of an equal tempered scale is disclosed in which a note voltage generator circuit includes a plurality of first resistors connected in series between first and second terminals, a plurality of second resistors each connected between the connection point of adjacent ones of the plurality of first resistors and a third terminal common to the first and second resistors and third and fourth resistors connected between the first and third terminals and the second and third terminals, respectively; at least the connection points of adjacent ones of the plurality of first resistors are connected through the keyboard switches to the one end of a DC power source connected at the other end to the third terminal; out put terminals are led out from the first and third terminals or the mid point of the third resistor and said third terminal; and the values r and R of the first and second resistors and the values R0 of the third and fourth resistors are determined by the diminishing ratio between adjacent notes of the equal tempered scale.

v United States Patent Mieda 1 Nov. 11, 1975 1 1 MONOPHONIC ELECTRONIC MUSICAL 3.766.305 /1973 Schrecongost 84/101 INSTRUMENT OF EQUAL TEMPERED 3.7860166 1/1974 Mieda 84/101 SCALE 3.801721 4/1974 Bunger 8-1/DlG. 2

3818.1 6/1974 Hirano [75] Inventor: Fumio Mieda, Tokyo, Japan 3.828.108 8/1974 Thompson R27 983 41974 St 1 84/101 [73] Assigneez Kelo Giken Kogyo Kabushikikaisha, edmq Tokyo Japan Primarr Examiner stephen J. 'Iomsky [22] Filed: Sept. 11, 1974 Assistant Emminer-Stanley .1. Witkowski [21] Appl. No; 504,878 Attorney, Agent, or Firm-Marshall & Yeastmg 57 ABSTRACT Foreign Application Priority Data 1 Se t 14 1973 h an 48 104176 A monophomc electronic musical instrument of an p p equal tempered scale is disclosed in which a note voltage generator circuit includes a plurality of first resis- [52] 84/101 84/1316 Z g d tors connected in series between first and second ter- [51] lm. c1. 0101! 1/02; @1011 5/02 mmals a Olseconfj each Connected between the connection point of adjacent ones of the [58] Field of Search 84/1.0l, DlG. 2, DIG. 8, 4 I

84/1316 1 74 plurality of first reslstors and a third terminal common 7 to the first and second resistors and third and fourth [56] Refere ces Cited resistors connected between the first and third terminals and the second and third terminals, respectively; UNITED STATES PATENTS at least the connection points of adjacent ones of the 2.403664 7/1946 Langer 84/D1G. 20 plurality of first resistors are connected through the 2.933.699 4/1960 Bonham 84/DIG. 20 keyboard switches to the one end of a DC power 1963932 12/1960 Cutler 84/101 source connected at the other end to the third termimggg g 21 nal; out put terminals are led out from the first and 2 5 amp e r no third terminals or the mid point of the third resistor /l966 George 84/101 3 395 242 7/1968 Human" v U 84/DIG 2 and said third termlnal; and the values 7' and R of the 1 H1970 George 84/m1 first and second resistors and the values R of the third 55 7 3/1973 Adachi D I e H 84/134 X and fourth resistors are determined by the dimmlshmg 3666875 5/1972 Ranzato 84/1724 X ratio between adjacent notes of the equal tempered 3,733,955 5/1973 Reinagel et all 84/l.0l scale. 3,745,225 7/1973 Hall 84/124 X 3,764,723 10/1973 Takeyama 84/1.01 3 4 Drawlng Figures 8a OSCILL/ATOR AMPLIFIER I .SPEAKER U.S. Patent N v.11, 1975 Sheet1of2 3,918,342

FIGJ

MONOPHONIC ELECTRONIC MUSICAL INSTRUMENT OF EQUAL TEMPERED SCALE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to improvements in a monophonic electronic musical instrument of an equal tempered scale which has keyboard switches corresponding to notes of the equal tempered scale, a note voltage generator circuit from which a note voltage corresponding to each of the keyboard switches can be obtained by depressing each of the keyboard switches, an oscillator for producing a tone signal having a frequency corresponding the note voltage, an amplifier foramplifying the tone signal and a speaker connected to the amplifier.

2. Description of the Prior Art In conventional note voltage generator circuits for monophonic electronic musical instrument of the above type, a corresponding number of resistance circuits to that of notes of the equal tempered scale are connected to a DC power source and the resistance values of the resistance circuits are adjusted in the manner of trial and error, by which signals having frequencies corresponding to the notes of the equal tempered scale are derived from a voltage control oscillator. This is based on such a concept that it is sufficient only to obtain monotones corresponding to the notes of the equal tempered scale by selectively depressing keyboard switches one after another.

Accordingly, the note voltage generator circuit heretofore employed in this kind of monophonic electronic musical instruments is constructed to include a variable resistor for each of the resistance circuits corresponding to the notes, and hence is complicated, bulky and expensive in its overall circuit construction and, in addition, involves troublesome adjustment of the resistance values of the individual resistance circuits corresponding to the notes.

SUMMARY OF THE INVENTION Accordingly, the present invention has for its object to provide a monophonic electronic musical instrument which is free from the aforesaid defects experienced in the prior art.

Other objects, features and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawrngs.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing one example of a monophonic electronic musical instrument of the equal tempered scale according to this invention;

FIG. 2 is a graph showing the relationships of voltages and frequencies of signals corresponding to notes to selection switches, for explaining this invention; and

FIGS. 3 and 4 are block diagrams illustrating other examples of this invention, respectively.

DESCRIPTION OF PREFERRED EMBODIMENTS In FIG. 1, reference numeral 1 indicates generally a note voltage generator circuit according to this invention. Between terminals 2 and 3 are sequentially connected in series (n-l) s resistors X X and X,,., where n indicates the last term or the number of terms in a series of similar terms. Resistors Y Y and Y,,

are connected between a common line shown extending between terminals 4 and the junctions P between the resistors X including the end junctions P and P,, connected to terminals 2 and 3 respectively. In addition terminating resistors keyboard switches S S and 5,, to the one end of a DC power source 7 connected at the other end to the terminal 4. Further, a pair of output terminals 8,, and 8,, are connected to the terminals 2 and 4, respectively. In this case, the resistors X, to X,, have the same resistance value r and the resistors Y to Y have also the same resistance value R. Further, the resistance values of the resistors 5 and 6 are selected to be those R and R which are substantially equal to image impedances viewed from the terminals 2 and 4, and 3 and 4 to the sides of the terminals 3 and 4, and 2 and 4, respectively. (In this case, since R =R these values will hereinafter be referred to as R,,.) Accordingly, if voltages which are obtained between output terminals 8,, and 8,, by sequentially depressing the switches S S and S,, are taken as e e and 2,, and if K is taken as a constant, output voltages e e and e,, (where e, e e,,) bearing the following relationships are derived from between the output terminals 8,, and 8,,.

By sequential depression of the keyboard switches S S and S,, in such a note voltage generator circuit 1, the voltages e e and e,, are sequentially obtained between the output terminals 8,, and 8,, and supplied to an oscillator 9, from which are sequentially derived tone signals F F and F, having frequencies f,, f and f,,, respectively. In this case, the oscillator 9 is one that its input voltage versus frequency characteristic is linear, so'that; the frequencies f,, f;, and f,, of the tone signals F F and F,, derived from the oscillator 9 bear the following relationships:

With such an arrangement as set forth above, in the note voltage generator circuit 1, the tone signals of the frequencies f f and f,,, sequentially derived from the oscillator 9 by sequential depression of the switches S S and 8,,, are supplied through an amplifier 10 to a speaker 11. Accordingly, if the switches S S and S,, are selectively depressed one after another, notes of the frequencies f,, f and f are sequentially produced from the speaker 11. In this case, the frequencies f to f,, bear the relationships given by the equation (2), so that, by sequentially depressing the switches S S and 8,,, the equal tempered scale having a constant diminishing ratio between adjacent notes respectively can be obtained. FIG. 2 shows the relationships of the voltages e e and e supplied to the oscillator 9 and the frequencies f f and f of the tone signals from the oscillator 9 to the switches S S and S The solid line indicates the abovedescribed case. The dash line and the chain line illustrate the corresponding relations when the X resistor of each section of the attenuator is subdivided as shown in FIGS. 3 and 4.

By the way, the diminishing ration between adjacent notes employed in monophonic electronic musical in- Accordingly. with the above construction. when the switches S S and S,, of the note voltage generator circuit 1 are selectively depressed one after another.

theequal tempered scale having a constant diminishing ratio between adjacent notes can be obtained, so that the keyboard switches S to S,, are arranged from the higher part of notes toward the lower part of notes. Further, the resistance values r, R and R of the resistors X to X,, Y to Y,, and and 6 in the case of K of the aforesaid equation l being 11 bear the following relationships:

Accordingly, in the note voltage generator circuit 1, the values of the aforementioned resistors X to X,, Y to Y,, and 5 and 6 are so selected as to satisfy the equations (4) and (5).

Thus. if anyone of the values r, R and R in the equations (4) and (5) is determined, these values can all be determined. For example, if r==lKQ, the equations (4) and (5) become as follows:

vator circuit independent resistance circuits each corresponding to each note as in the prior art and, further, each resistance circuit need not be constructed to include a variable attenuator. Moreover, this invention the case of depressing the switches S S S has a great advantage that the ordinary equal tempered scalecan be moderately obtained without adjusting the resistance value of eachresistance circuit corresponding to each note. I

The foregoing description has been given with regard to the case where onlythe connection points P P and P, of the terminal 2 and the resistor X the resistors X and X the resistors X and X the resistors X,, and X and the resistor X,, and the tenninal 3 are connectedto the keyboard switches S S and 8,, in the note voltage generator circuit 1. However, it is also possible to employ such a circuit con- .struction as shown in FIG. 3, in which parts correspondingto those in FIG. 1 are marked with the same reference numerals and characters. Namely, the values r, R and R of the resistors X, to X,, Y to Y, and 5 and 6 are so selected as to satisfy the following equations corresponding to the aforesaid ones (4) and (5):

The connection points P P P and P1, of the terminal 2 and the resistor X the resistors X and X the resistors X and X the resistors X,, and X,, and the resistor X and the teminal 3 are connected to the power source 7 through the keyboard switches S S S and S respectively. Further, points P P P and P,, led out from the mid points dividing the resistors X X and X,, into two respectively, are connected to the power source 7 through the keyboard switches S S S and 5 respectively.

Thus, since the equations (8) and (9) are satisfied, in

. one after another, voltages drived between the output terminals 8,, and 8,, are the same as the voltages e e e obtained in the case of FIG. 1. However, in the case of depressing the switches S S S one after another, if the values of the resistors X to X on the sides of the terminal 2 and 3 from their dividing points are taken as r and r, respectively, and if r x r, it

follows that e,r" 0:!" e r" e -,r' e r" e r' r r r and if r'=r=r/2, it follows that Accordingly, voltages e e e which are a little higher than the voltages e e e obtained by depressing the switches S S S in the case of FIG. 1. Therefore, it is preferred that r'= r= r/2 but, in any case, it is possible to an equal tempered scale close to the ordinary equal tempered scale. In FIG. 2, the broken line indicates the relationships of the voltages e e e e e e supplied to the oscillator 9 to the switches S S in the case of r'=r" in the example of FIG. 3, and the relationships of the frequencies f f ,f ,fl' ,f,,f of the signals derived from the oscillator 9 to the switches S S in this case. f f

indicate oscillation frequencies in the cases of the voltages e e FIG. 3 illustrates such a modified 'form of the note voltage generator circuit 1 in which the connection points P P P P,, and P of the terminal 2 and the resistor X the resistors X and X X and X X,, and X,, and the resistor X,, and the terminal 3 are connected to the power source 7 through the keyboard switches, respectively, and, in addition, the points P P and P,, led out from the dividing points of the resistors X to X,, are also connected to the power source 7 through the keyboard switches, respectively. Enlarging such an idea, it is also possible that points led out from .morethan two points dividing each of the resistors X to X into more than three are connected to the power source 7 through the keyboard voltages e e e which each of the resistors X to X,, is divided'is lim- 1 v ited to less than three.

FIG. 4 shows another modified form of this invention which is constructed in view of the above and inwhich' two points dividing each of the resistors X, to X,, of

the note voltage generator circuit 1 into three are con- S nected to the power source 7 through the keyboard swithces. In FIG. 4, parts corresponding to those in FIG. 1 are identified by the same reference numerals and characters and no detailed description will be repeated. The values r, R and R of the resistors X to X,, Y to Y,, and and 6 are so selected as to satisfy the following conditions corresponding to the aforesaid equations (4) and (5):

r IP

The connection points P P P P,, and? of the terminal 2 and theresistor X,, the resistors X, and X X and X X,, and X,, and the resistor X and the terminal 3 are connected to the power source 7 through the keyboard switches S S S and S Further, points P and p P and p P,, and P,, led out from two points dividing each of the resistors X to X,, are connected to the power source 7 through the keyboard switches S and S S and S 3n-4 and 3(n-l)- With such an arrangement, since the conditions of the equations (l0)'and (11) are satisfied, when the switches 5 S S are sequentially depressed, the voltages derived between the output terminals 8,, and 8,, are the same as the voltages e e e obtained in the case of the example of FIG. 1. However, where the switches S S S are depressed one after another, if the values of the respective portions of each of the resistors X to X,, devided into three, that is, the portion on the side of the terminal 2, the central portion III as r', r" and r and if r a; r": r', it follows that and if r=r"'=r"'=r/3, it follows that and voltages e e e a little higher than the obtained by depressing the I the relationships of the frequencies f f f 'f, f f

6 theswitches S 5 :8 I. ,ifr' r" a 'r as described above, it follows that I and if r'=r"=r=r/3, it follows that and voltages e e e,,, a little higher than the voltages e e e,,, obtained by depressingthe switches S S S in the case of FIG. 1, areob? tained. Consequently, it is, preferred that r=r=r")t =r/3 but, in any case, an equal tempered scale approximate to the ordinary equal tempered scale can be obtained. In FIG. 2, the chain line indicates the relationships of thevoltages e e e e e5", e e plied tothe oscillator 9 to the switches-8 ,5 and ",1}, of the signals derived from the oscillator 9 to the switches S S in this case.f ",f f indicate the oscillation frequencies ;of the voltages switches S S S in the case of FIG. 1, are ob- I tained. Further, in the case of sequentially depressing Although the foregoing description has been given in connection with the case. where the output terminals 8,, and8 of the note voltage generatorcircuit l are led out'from the terminals2 and*4, they canbe led out from a desired or pointadjustable 2 of the resistor 5 and-the terminal 4 to raise'or lower the pitch of allv notes of the scale. as required to tune the instrument to a standard pitch.v 1 t It will be apparent that-many modifications and variations. may be effected without departing from the scope. of the novel concepts of this invention. I

I claim as my-invention:

l. A monophonic electronic musical instrument of an equal tempered scale comprising keyboard switches corresponding to notes of said equal tempered scale, a note voltage generator circuit for producing a note voltage corresponding to each of said keyboard switches in response to the depression of each of the keyboard switches, an oscillator for producing a tone signals having a frequency corresponding to said note voltage, 'an amplifier for amplifying said tone signal, and a speaker connected to said amplifier, characterized in that said note voltage generator circuit includes a plurality of first resistors connected in series between first and second terminals, a'plurality of second resistors each connected between the connection point of adjacent ones of said plurality of first resistors and a third terminal common to said first and second resistors and third and fourth resistors connected between said first and third terminals and said second and third terminals, respectively; the connection points of adjacent ones of said plurality of first resistors are connected through said keyboard switches to the one end of a DC power source connected at the other end to said third terminal; output terminals are led out from said first and third terminals or the mid point of said third resistor and said third terminal; and if the diminishing ratio between adjacent notes of the equal tempered scale is taken as 1 if the values of said first and second resistors 1 are taken as r and R, respectively; and if the values of said third and fourth resistors are taken as R", they bear the following relationships:

and a speaker connected to said amplifier, character- I ized in that said notevoltagc generator circuit includes a plurality of first resistors connected in series between first and second terminals, a plurality of second resistors each connected between the connection point of adjacent ones of said plurality of first resistors and a third terminal common to said first and second resistors and third and fourth resistors connected between said first'and third terminals and said second and third terminals, respectively; the connection points of adjacent ones of said plurality fo first resistors and one point of each of said plurality of first resistors dividing it into two are connected through said keyboard switches to the one end of a DC power source conected at the other end to said third terminal; output terminals are led outfrom said first and third terminals or the mid point of said third resistor and said third terminal; and if the diminishing ratio betwen adjacent notes of the equal tempered scale is taken as 17, if the values of said first and second resistors are taken as r and R, respectively; and if the values of said third and fourth resistors are taken as R they bear the following relationships:

3. A monophonicelectronic musical instrument of an equal tempered scale comprising keyboard switches corresponding tonotes of said equal tempered scale, a note voltagegenerator-circuit for producing a note voltage corresponding to each of said keyboard switches in response to the depression of each of the keyboard switches, an oscillator for producing a tone signal having a frequency corresponding to said note voltage, an amplifier for amplifying said tone signal, and a speaker connected to said amplifier, characterized in that said note voltage generator circuit includes a plurality of first resistors connected in series between first and second terminals, a plurality of second resistors each connected between the connection point of adjacent ones of said plurality of first resistors and a third terminal common to said first and second resistors and third and fourth resistors connected between said first and third terminals and said second and third terminals, respectively; the connection points of adjacent ones of said plurality of first resistors and two points of each of said plurality of first resistors dividing it into three are connected through said keyboard switches to the one end of a DC power source connected at the other end to said third terminal; output terminals are led out from said, first and third terminals or the mid point of said third resistor and said third terminal; and

if the diminishing ratio between adjacent notes of the equal tempered scale is taken as 1 if the values of said first and second resistors are taken as r and R,,respectively; and if the values of said third and fourth resistors are taken as R,,, they bear the following relationships: 

1. A monophonic electronic musical instrument of an equal tempered scale comprising keyboard switches corresponding to notes of said equal tempered scale, a note voltage generator circuit for producing a note voltage corresponding to each of said keyboard switches in response to the depression of each of the keyboard switches, an oscillator for producing a tone signals having a frequency corresponding to said note voltage, an amplifier for amplifying said tone signal, and a speaker connected to said amplifier, characterized in that said note voltage generator circuit includes a plurality of first resistors connected in series between first and second terminals, a plurality of second resistors each connected between the connection point of adjacent ones of said plurality of first resistors and a third terminal common to said first and second resistors and third and fourth resistors connected between said first and third terminals and said second and third terminals, respectively; the connection points of adjacent ones of said plurality of first resistors are connected through said keyboard switches to the one end of a DC power source connected at the other end to said third terminal; output terminals are led out from said first and third terminals or the mid point of said third resistor and said third terminal; and if the diminishing ratio between adjacent notes of the equal tempered scale is taken as Eta , if the values of said first and second resistors are taken as r and R, respectively; and if the values of said third and fourth resistors are taken as R0, they bear the following relationships:
 2. A monophonic electronic musical instrument of an equal tempered scale comprising keyboard switches corresponding to notes of said equal tempered scale, a note voltage generator circuit for producing a note voltage corresponding to each of said keyboard switches in response to the depression of each of the keyboard switches; an oscillator for producing a tone signal having a frequency corresponding to said note voltage, an amplifier for amplifying said tone signal, and a speaker connected to said amplifier, characterized in that said note voltage generator circuit includes a plurality of first resistors connected in series between first and second terminals, a plurality of second resistors each connected between the connection point of adjacent ones of said plurality of first resistors and a third terminal common to said first and second resistors and third and fourth resistors connected between said first and third terminals and said second and third terminals, respectively; the connection points of adjacent ones of said plurality fo first resistors and one point of each of said plurality of first resistors dividing it into two are connected through said keyboard switches to the one end of a DC power source conected at the other end to said third terminal; output terminals are led out from said first and third terminals or the mid point of said third resistor and said third terminal; and if the diminishing ratio betwen adjacent notes of the equal tempered scale is taken as eta , if the values of said first and second resistors are taken as r and R, respectively; and if the values of said third and fourth resistors are taken as R0, they bear the following relationships:
 3. A monophonic electronic musical instrument of an equal tempered scale comprising keyboard switches corresponding to notes of said equal tempered scale, a note voltage generator circuit for producing a note voltage corresponding to each of said keyboard switches in response to the depression of each of the keyboard switches, an oscillator for producing a tone signal having a frequency corresponding to said note voltage, an amplifier for amplifying said tone signal, and a speaker connected to said amplifier, characterized in that said note voltage generator circuit includes a plurality of first resistors connected in series between first and second terminals, a plurality of second resistors each connected between the connection point of adjacent ones of said plurality of first resistors and a third terminal common to said first and second resistors and third and fourth resistors connected between said first and third terminals and said second and third terminals, respectively; the connection points of adjacent ones of said plurality of first resistors and two points of each of said plurality of first resistors dividing it into three are connected through said keyboard switches to the one end of a DC power source connected at the other end to said third terminal; output terminals are led out from said first and third terminals or the mid point of said third resistor and said third terminal; and if the diminishing ratio between adjacent notes of the equal tempered scale is taken as eta , if the values of said first and second resistors are taken as r and R, respectively; and if the values of said third and fourth resistors are taken as R0, they bear the following relationships: 